Land Recent QUIC changes.

net/quic/quic_received_entropy_manager.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Manages the packet entropy calculation for both sent and received packets
+// for a connection.
+
+#ifndef NET_QUIC_QUIC_RECEIVED_ENTROPY_MANAGER_H_
+#define NET_QUIC_QUIC_RECEIVED_ENTROPY_MANAGER_H_
+
+#include "net/quic/quic_framer.h"
+#include "net/quic/quic_protocol.h"
+
+namespace net {
+
+// Records all received packets by a connection to track the cumulative
+// entropy of received packets.  Also, called by the framer when it truncates
+// an ack frame to calculate the correct entropy value for the ack frame being
+// serialized.
+class NET_EXPORT_PRIVATE QuicReceivedEntropyManager :
+    public QuicReceivedEntropyHashCalculatorInterface {
+ public:
+  QuicReceivedEntropyManager();
+  virtual ~QuicReceivedEntropyManager();
+
+  // Record the received entropy hash against |sequence_number|.
+  void RecordPacketEntropyHash(QuicPacketSequenceNumber sequence_number,
+                               QuicPacketEntropyHash entropy_hash);
+
+  // QuicReceivedEntropyHashCalculatorInterface
+  // Called by QuicFramer, when the outgoing ack gets truncated, to recalculate
+  // the received entropy hash for the truncated ack frame.
+  virtual QuicPacketEntropyHash EntropyHash(
+      QuicPacketSequenceNumber sequence_number) const OVERRIDE;
+
+  QuicPacketSequenceNumber LargestSequenceNumber() const;
+
+  // Recalculate the entropy hash and clears old packet entropies,
+  // now that the sender sent us the |entropy_hash| for packets up to,
+  // but not including, |peer_least_unacked|.
+  void RecalculateEntropyHash(QuicPacketSequenceNumber peer_least_unacked,
+                              QuicPacketEntropyHash entropy_hash);
+
+  QuicPacketEntropyHash packets_entropy_hash() const {
+    return packets_entropy_hash_;
+  }
+
+ private:
+  typedef std::map<QuicPacketSequenceNumber,
+                   QuicPacketEntropyHash> ReceivedEntropyMap;
+
+  // TODO(satyamshekhar): Can be optimized using an interval set like data
+  // structure.
+  // Map of received sequence numbers to their corresponding entropy.
+  // Every received packet has an entry, and packets without the entropy bit set
+  // have an entropy value of 0.
+  // TODO(ianswett): When the entropy flag is off, the entropy should not be 0.
+  ReceivedEntropyMap packets_entropy_;
+
+  // Cumulative hash of entropy of all received packets.
+  QuicPacketEntropyHash packets_entropy_hash_;
+
+  // The largest sequence number cleared by RecalculateEntropyHash.
+  // Received entropy cannot be calculated for numbers less than it.
+  QuicPacketSequenceNumber largest_sequence_number_;
+};
+
+}  // namespace net
+
+#endif  // NET_QUIC_QUIC_RECEIVED_ENTROPY_MANAGER_H_